Sarcoidosis is a chronic disease that often involves the lungs; its cause is unknown. The ACCESS Study (A Case Control Etiologic Study of Sarcoidosis) will compare facts about patients with sarcoidosis (cases) and people without sarcoidosis (controls) to learn what causes the disease. Ten clinic research centers from across America are in this study. The ACCESS Study is a research project of the National Institutes of Health. The ten clinics will enroll a total of 720 cases for the study. Also, 720 controls will enroll in the study. Data and blood samples will be collected from the controls to compare with the data and blood samples from patients with sarcoidosis. Only patients with newly found sarcoidosis, on biopsy, are asked to join this study. If these patients agree to participate, there will be five parts of this study. First is an interview to record medical, environmental, and family history. Second is a physical examination by a doctor on the research team. Third, clinic staff will take a sample of the patient's blood. Fourth, clinic staff will perform or review the results of tests that are part of the usual care for sarcoidosis. Fifth, clinic staff will contact cases every six months for two years and see them in the clinic two years after they join the study. This follow-up appointment two years after the initial visit will require one to two hours of time. Cases and controls will be paid for their time and effort participating in ACCESS. None of the testing costs will be passed onto a case or control. Potential causes of sarcoidosis which are explored in this study are genetic predispositions, occupational and environmental exposures, place of residence, medication usage, and organ involvement and what it means for disease stability or progression. The cause of sarcoidosis may not prove to be a single, known exposure. Interactions of exposures with genetic predispositions would have important implications for our understanding of immune system responses as well as the origin and development of sarcoidosis.